Ammonium bicarbonate which can be also substituted by Potassium bicarbonate because the anion is the important part for the baking which is the same in both compounds.

Baking powder is made from 2 parts Baking Soda and 1 part Cream of Tartar.

-  Ammonium Biocarbonate is activated when :-

1)  it is added to a dough or batter mixture

2)  it is warms to room temperature/baked.
     Heat is the catlyst to activate the chemical reaction and the gases. 
     The chemical reaction releases an ammonia gas that causes the baked goods to rise. 

-  Ammonium Biocarbonate should be stored in an airtight sealed container such as a glass jar with an airtight lid.  When properly stored in a cool dry area, Ammonium Bicarbonate can last for several years.  If stored in a warm or damp area where air can reach the powder, this substance begins to clump together as the particles go through a chemical reaction, which will affect the flavor adversely when baked goods use the air-exposed Bicarbonate. In addition, when exposed to air, the Ammonia may begin to evaporate from the powdered Bicarbonate substance. 

-  When a recipe suggests the use of Ammonium Bicarbonate, equal amounts of baking powder can be substituted if necessary. 

-  To determine if Bicarbonate is still active, add a spoonful of the powder to a cup containing lemon juice or vinegar and see if it fizzes. 

-  Stale Ammonium Bicarbonate will be flat and will not fizz when combined with the vinegar or lemon juice.

Bun:

8g instant dry yeast
160ml lukewarm water
½ tsp white vinegar or lemon juice (optional)
280g low-protein Hongkong flour
100g wheat starch
90g icing sugar
30g shortening or vegetable oil

10g baking powder
10ml cold water

1.  Sift together flours and icing sugar. 
2.  Place sifted flour mixture in a large mixing bowl and, 
3.  Make a well in the middle.
4.  Fill well with lukewarm water, vinegar and yeast. 
5.  Use a spatula, gently stir the water to dissolve the yeast then slowly bring together flour mixture.
6.  Uli hingga tepung sebati sehingga bila tarik macam chewing gum tak putus.
7.  Add in shortening or oil and knead for 10-15 minutes until soft dough is formed. 
8.  It should be smooth on the surface.
9.  Cover dough with damp cloth and let it rise for 30 minutes or until it is doubled in size.
10.Dissolve baking powder in COLD WATER, sprinkle over dough and knead until well combined.
11.There is no need to rest the dough after adding in baking powder, but if time allowed, rest it for 10 minutes or so to get fluffier buns.


PAU FROZEN (modified)
special pow flour (Hong Kong) RM6.40 sekilo

 450 g     Tepung HongKong
 230 g      Air                        
1  tbsp     Susu Pekat Manis
  5  tsp     Yeast   (6 g)              

Uli 1st                -    Uli hingga rata
Ferment  1st      -    30 minit

300 g       Tepung Hong Kong                                        
100 g       Gula Castor                                                    
2 tbsp       D/A Baking Powder  
  40 g       Shortening                                          
  1 tsp       Bread Softener   (4 g)                                
                                                                                       
100 g                              Air                                 )                              
1/3 rata sudu 1/4 tsp      Ammonium Carbonate   )  Larutkan rata-rata
 1 tsp                              Garam                           )                                

Uli ke 2           -  20 minit
Ferment 2      -  30 mnit
Bulatkan         -  20 g
Ferment 3      -  30 minit
Steam            -   Besar 15 minit
                          Kecil 8 minit

AIR KUKUS MESTI MENGGELEGAK
JANGAN OVERSTEAM NANTI PAU KUNING

CARA MENGUKUS PAU FROZEN:

Panaskan pengukus, terus kukus pau tanpa perlu 'defrost' (api sederhana).


PASTIKAN:

• Masa buat doh pau tu...make sure uli sampai doh kenyal (mcm getah yg elastik...ditarik xputus)
• Kadang2 ada yg xtau cmne nk rendam yis supaya kembang dgn cantik...time rendam yis..make sure tambah gula lbh kurg 2 sudu kcil dn gaul terlebih dahulu hingga rata..baru masukkan  air SUAM2 KUKU...tutup bekas merendam yis tu..jgn bg terdedah...kalau yis yg ok..patutnya..3mins dh kembang cantik...
• Buat inti dulu baru buat doh...kalau rs2 nk mkn pau esok hari...mlm ni buat inti dulu n sejukkn dlm peti ais...esok panaskn je kjap b4 masukkn dlm doh..(jimat masa)

Notes:

1.  Cover dough with damp cloth and let it rise for 30 minutes or until it is doubled in size. 

2.  Dissolve baking powder in cold water, sprinkle over dough and knead until well combined.

3. There is no need to rest the dough after adding in baking powder, 

     BUT  if time allowed, rest it for 10 minutes or so to get fluffier buns.

4.  If there are yellowish spots on the steamed buns, 

     IT MEANS the baking powder is not fully dissolved.

5.  Steamer must be preheated otherwise bun would not rise to the volume as it should be.

6.  Arrange buns into a steamer, leave about 1” gab in between buns. 

7.  Spray the surface of bun with water mist helps to produce buns with smooth surface after steamed.Spray water mist over buns, and steam in a preheated steamer on high heat for 12 minutes.

8.  Adding a few drops of white vinegar into steaming water will produce whiter buns, but this is optional. 

9.  DO NOT open the lid during the steaming process.

10.Remove buns from steamer and cool on rack to prevent soggy bottom.